This invention relates to a swash-plate type compressor for compressing refrigerant circulating in the refrigerating circuit of an air conditioning system, or like fluid, and more particularly to a novel and efficient oil separating arrangement provided in such type compressor for separating oil from refrigerant or like fluid.
Conventionally, swash-plate type compressors are widely used as one of the compressors for compressing refrigerant circulating in an air conditioning system. A compressor of this type generally includes a cylinder block having a plurality of axial cylinder bores within which pistons are slidably received, a pair of cylinder heads rigidly mounted at the opposite ends of the cylinder block with valve plates intervening therebetween, a drive shaft extending through the cylinder block and one of the cylinder heads along their axes, and a swash plate arranged within a swash plate chamber defined within the cylinder block and rigidly fitted on the drive shaft in engagement with the pistons via shoes and balls. The drive shaft is radially supported by radial bearings, and the swash plate axially supported by thrust bearings.
In this compressor, lubricating oil is fed to sliding machine parts such as the drive shaft, the swash plate, the pistons and the bearings, to lubricate them. That is, lubricating oil stored in an oil sump located below the swash plate is splashed into oily mist to be fed to the swash plate, the thrust bearings, the balls, the shoes, the pistons, etc. to lubricate them. The oil which is fed to the pistons to lubricate the same is sucked into the compression chambers through the gaps between the pistons and the cylinder bores and then discharged into the refrigerating circuit together with compressed refrigerant.
An increased amount of oil in the refrigerating circuit causes a deterioration in the performance of the heat exchanger of the air conditioning system, leading to an inferior refrigerating capacity of the system. Further, the increased amount of oil in the refrigerating circuit causes a shortage of oil within the compressor and consequently insufficient feeding of oil to the sliding machines parts, resulting in seizure of these parts.
It is therefore necessary to separate lubricating oil entrained in the refrigerant in an efficient manner and retain the oil thus separated within the compressor.